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Climate change associated with atmospheric warming and depletion of the earth’s protective ozone layer are two separate but interrelated problems, intersecting in complex ways that challenge easy comprehension and also efforts to address them. Recent developments related to chemicals commonly known as HFCs illustrate the situation.

Industrial emissions of carbon dioxide, the chief greenhouse gas produced through human activity and blamed for global warming, started long before the widespread use of refrigerant chemicals later discovered to be depleting stratospheric ozone.

The threat to the ozone layer, which blocks ultraviolet radiation harmful to living organisms, was the issue that commanded world attention first, however. Mounting concerns over the “ozone hole” led to the adoption in 1987 of the Montreal Protocol, the landmark international agreement to phase out production and use of the main ozone-destroying substances – chlorofluorocarbons, or CFCs.

The frequently amended Montreal treaty is regarded as a model for successful, global-scale environmental protection. Scientists project, for example, that the most dramatic example of ozone depletion – the mammoth hole in the ozone layer over Antarctica, first documented in 1985 – now could well be closed in several decades.

Vexing problems remain, however, that illustrate how the ozone issue is connected to the science of greenhouse warming and attempts to slow it.

Besides eroding the ozone layer, CFCs are also powerful greenhouse gases. The United Nations says that banning them has helped forestall the pace of global warming by up to a dozen years. Researchers have recently warned, however, that new findings point to increased temperatures across Antarctica if the hoped-for closing of the ozone hole ends up reversing a cloud-forming phenomenon, associated with depleted ozone there, that has shielded that region from some warming.

Efforts to mitigate climate change, meanwhile, have been complicated by scientific findings that HFCs – certain “ozone-friendly” refrigerant chemicals formally known as hydrofluorocarbons, introduced to substitute for CFC-replacing, but also ozone-depleting, chemicals (hydrochlorofluorocarbons or HCFCs) – are highly potent greenhouse agents in their own right. Using more of those ozone-friendly substitutes could end up boosting global warming even as they help address the stratospheric ozone depletion problem.

Passing the HFCs Baton … But to Whom?

Because of heightened concerns about HFCs’ role in global warming, two initiatives considered at an international conference on the Montreal Protocol last November in Port Ghalib, Egypt, sought to phase down use of those chemicals. Neither was adopted.

Instead, the negotiators in Egypt handed the issue to the Copenhagen climate conference in December, which also failed to take action on it, leaving the diplomatic picture on HFCs unclear.

The House-passed American Clean Energy and Security Act (the Waxman-Markey bill) would cap HFC emissions and regulate their production and imports, but prospects for measure or any energy-climate legislation to become law this year are far from certain.

The Environmental Protection Agency’s endangerment finding on greenhouse gases in December – a necessary precursor to administratively imposed restrictions under the Clean Air Act – targeted HFCs along with carbon dioxide and other substances. The outcome of that process is also unclear, however, and some members of Congress are trying to prevent the EPA from adopting regulations, which, if fully adopted, would inevitably lead to litigation.

Even in the absence of regulatory requirements, however, a number of corporations, prodded and encouraged by environmental groups, have been moving ahead with tests of other refrigerant substances that could be used in lieu of HFCs.

Coca-Cola, for instance, announced in December that it would eliminate HFCs from its new vending machines and coolers by 2015 – an action that Reuters reported had “rais(ed) the bar for climate-friendly refrigeration in the food and beverage industry.”

“There are a number of things moving that are positive,” said Kert Davies, research director of Greenpeace USA, which issued a report in December analyzing the HFC-related actions of 18 companies, offering both praise and criticism.

“There’s a big ball of pressure and 2009 was a banner year for stigmatization of HFCs,” Davies told The Yale Forum. “There’s a lot going on that ultimately, we think, will tip the scale toward alternatives (to HFCs) coming to the market. Our work is to make that happen faster and faster.”

No Agreement at Two Diplomatic Meetings

HFCs have been dubbed “super greenhouse gases” because, molecule for molecule, their global warming effect is hundreds of times greater than carbon dioxide’s. Still, their long-recognized role in the climate issue has been relatively obscure. Trying to raise that profile, Greenpeace’s report in December called HFCs “the worst greenhouse gases you’ve never heard of.”

That may change, in part because of two new EPA rules, announced in December to comply with the Montreal Protocol. The rules will reduce the availability and use of HCFCs, whose ozone-depleting power is less than that of CFCs but still worrisome enough to prompt their restriction under the ozone treaty. The HCFC phase-down focuses more attention on HCFC-replacing HFCs, their warming potential, and on various alternatives to HFC use.

The HFC-warming issue has not gotten anything close to the media attention that the debate over reducing CO2 emissions has received, but SolveClimate is one news outlet that has continued to follow it closely. The internet publication’s coverage last year included articles on jockeying within the Obama administration over whether the Montreal Protocol or a climate treaty is the best vehicle for reducing HFC use, then on the issue’s handling at the Egypt and Copenhagen conferences.

After the meeting on the Montreal Protocol in Egypt ended, for example, an analysis by SolveClimate founder David Sassoon assessed the issue’s diplomatic status and immediate prospects. In the article, also distributed by Reuters, he reported that the U.S. delegation was “shocked” that its proposal to phase down HFCs was “soundly rebuffed”:

Even though the stakes for the global environment are very high, the meeting ended with no amendment and no binding decision on HFCs. Instead, 41 out of 198 countries signed a weak “declaration of intent.”

Advocates are doing their best to put a happy face on the outcome, but the failure to act on phasing down HFCs is a disappointment, and it provides a preview of an outcome that many fear may be repeated on a larger scale in Copenhagen.

Achim Steiner, executive director of the U.N. Environment Programme (UNEP), issued a statement after the Port Ghalib meeting, in which he described the HFC issue as increasingly linked to broader negotiations aimed at dealing with climate change: “Clearly the sooner the international community seals the deal on climate change, the sooner other related agreements can move forward.”

Many scientists and environmentalists say reducing the “forgotten 50 percent” of pollutants will be faster, easier and substantially cheaper than cutting carbon dioxide, and could buy the world time in its climate clock race.

Tankersley reported that negotiators were “quietly making progress” on these lower-profile greenhouse gases. Their eventual failure to reach agreement on the issue, however, left a cloudy diplomatic road ahead. Besides another major climate conference convening in Mexico in November (where, an analysis in The Guardian concluded this month, a binding deal already seems “all but impossible,”), a separate series of U.N.-sponsored meetings this year will address possible changes to the Montreal Protocol.

A blog on the website of the scientific journal Naturereported that delegates to the Port Ghalib conference “called on a technical committee to analyze alternatives to (HFCs) in advance of a potential decision” in 2010.

A New Chapter in an Old Debate

Scientific findings have continued to add urgency to the HFC-related decisions facing policymakers at the national and international levels.

Last June, for instance, in the journal Proceedings of the National Academy of Sciences, scientists from the Netherlands Environmental Assessment Agency, two U.S. agencies, and Du Pont published a paper projecting “substantially” growing use and emissions of HFCs – larger than in previous forecasts – if those chemicals replace HCFCs without regulation.

They wrote that the projected increases “result primarily from sustained growth in demand for refrigeration, air-conditioning and insulating foam products in developing countries,” based on anticipated economic growth there and on the prior experiences of developed nations.

Developing countries’ HFC emissions could range up to 800 percent greater than those of developed countries by mid-century, the researchers concluded.

They projected that without HFC restrictions, global emissions in 2050 would have a warming effect of up to 45 percent of projected CO2 emissions at that time, assuming that CO2 in the atmosphere is stabilized by then at 450 parts per million. That is the CO2 level that other experts project is necessary to limit the earth’s average temperature increase to about 2 degrees Celsius (3.5 degrees Fahrenheit).

Last November, researchers at NASA and Purdue University published a study in the American Chemical Society’s Journal of Physical Chemistry, which extended scientific understanding of the molecular mechanism explaining HFCs’ warming capacity.

They reported that their examination of HFCs and other fluorinated compounds, including CFCs, revealed that these chemicals are much more efficient than carbon dioxide and methane at trapping warming radiation in the frequency of the infrared region known as the “atmospheric window,” blocking its return to space.

Proponents of restricting HFCs are now citing such recent studies to underscore their argument that phasing down production and use of the chemicals affords an opportunity for relatively quick and substantial action against global warming while broader and far more complex efforts to reduce CO2 emissions proceed.

Regardless of whether the new research findings result in restrictions on HFCs through a global agreement, the question of what refrigerant substances to use in their place has been receiving increased attention.

In part, these developments represent a new chapter in a long-running debate – whether to use compounds developed by the chemical industry or “natural” refrigerants, such as hydrocarbons (without ozone-depleting and warming potential) and carbon dioxide (with far less warming capacity than HFCs).

Greenpeace has promoted “natural” substances through its GreenFreeze campaign since 1992, arguing that they are environmentally preferable to HCFCs and HFCs.

The group’s effort has included development of a GreenFreeze refrigerator, 300 million of which it says have been sold in Europe, Asia, and South America. The group also has also pressed corporations to change refrigerants. Coca-Cola, for instance, said its commitment in December to go HFC-free was the “direct result” of “increasingly cooperative” discussions with Greenpeace since 2000. The company said it has already started using hydrocarbon and CO2 cooling in smaller and larger equipment, respectively.

An emerging point of contention involves new refrigerant chemicals called hydrofluoroolefins, or HFOs.

Manufacturers are promoting them as an environmentally superior replacement for HFCs. Honeywell’s website, for instance, describes one hydrofluoroolefin – HFO-1234yf – as “a next generation fluorinated solution” that can meet climate-related rules in the European Union. The E.U. has banned the use of the HFC gas R-134a in vehicle air conditioners, starting in 2011, because of its contribution to global warming.

“Our alternative has the lowest life-cycle climate performance rating of any R-134a replacement option – including CO2 – due to its higher energy efficiency, which results in lower fuel consumption,” the Honeywell website text asserts.

Seeking to counter such appeals, Greenpeace issued a position paper on HFOs last October, arguing that, chemically, they are also HFCs, but are being marketed under a different name because of “the negative connotations that HFCs have acquired.”

The paper argued that HFOs are “only a short-term fix,” which presents “an unnecessary risk to the environment and human health” when compared to “natural” refrigerants.

In October, EPA proposed the listing of HFO-1234yf as a safe alternative for auto air conditioners, declaring that it does not deplete the ozone layer and “when used with proper risk mitigation technologies, will reduce the impact of (vehicle air conditioner) refrigerant emissions on the environment.”

The agency said HFO-1234yf has a “global warming potential” value of 4 – quadruple the value of 1 assigned to CO2, but far smaller than the value of 1,430 for R-134a and the value of 10,890 for CFC-12.